Clojure NullPointerException errors occurring - clojure

Question

I get a strange error when I load my Clojure project and I was wondering why it happens and why my workaround works:
I get a NullpointerException error when I start my clojure project with lein repl, which loads in one of my Clojure files (which contains a lot of functions). My workaround is that I comment out the main content of the the last 3 functions in the file and load the project. When there's no error message, I exit it, uncomment the parts (effectively restoring the initial file) and it finally loads and doesn't show any error messages.
It's kind of strange that it loads the second time but not the first time.
Does this happen to anyone else? I didn't include my code because it is 600+ lines of different functions.
Edit: Providing stack trace and full report. It seems to be only the -main function that causes the error. If I comment out the content (leaving only the header) and run lein repl, it compiles fine. Then I uncomment the content, and run lein repl, there is no NPE. Only after a while it happens again.
(defn -main [prev curr act cstm]
(if (or (nil? prev) (empty? prev))
curr
(let [other-prev-concepts (filter #(not(is-object %)) prev)
prev (filter #(is-object %) prev)
newpstm prev
newpstm (filter #(is-object %) newpstm)
newpstm (adjust-poses-from-camera-move (first act) newpstm)
other-curr-concepts (filter #(not(is-object %)) curr)
curr-cycle (filter #(is-object %) curr)
results (if (< (count curr-cycle) (count newpstm))
(map reverse (get (find-alignment curr-cycle newpstm) :assignments))
(get (find-alignment newpstm curr-cycle) :assignments))
aligned (filter #(< (apply get-distance %) maxWeight*) results)
mapped-pstm (map second aligned)
pstm-map (convert-to-map-of-map curr-cycle)
prev-map (convert-to-map-of-map newpstm)
newprev
(loop [remaining aligned
result {}]
(if (empty? remaining)
result
(let [[head & others] remaining
old (second (first head))
new (second (second head))
mapped-old (map second (map first aligned))
new-fields (get pstm-map new)
updated-prev (assoc result old new-fields)
conf (get-in prev-map [old :*conf])
new-conf (min (+ conf confInc*) 1)
updated-prev (assoc-in updated-prev [old :*conf] new-conf)
children (map second (filter #(and (= old (last %)) (= 'attached (first %))) cstm) )
children-to-update (remove (set mapped-old) children)
updated-prev (update-children (get prev-map old) (get pstm-map new)
children-to-update prev-map updated-prev cstm mapped-old)
]
(recur others updated-prev)
)
))
mapped-prev (map second (map first aligned))
newprev (convert-map-to-list newprev)
newprev (disapps act newpstm curr-cycle newprev cstm)
newprev (apps mapped-pstm curr-cycle newprev)
]
(concat newprev other-curr-concepts)
)
)
)
Stack trace:
$ lein repl
If there are a lot of uncached dependencies this might take a while ...
Compiling proj.core
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Executing python initialize with options:{:python-executable nil, :program-name nil, :python-home nil, :library-path nil}
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Detecting startup-info for Python executable:
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Startup info detected: {:python-home "/home/user/miniconda3/envs/usr", :lib-version "3.6", :libname "python3.6m", :java-library-path-addendum "/home/user/miniconda3/envs/usr/lib"}
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Setting java library path: /home/user/miniconda3/envs/usr/lib:/home/user/catkin_ws/devel/lib:/opt/ros/melodic/lib:/usr/java/packages/lib:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Reference thread starting
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Library python3.6m found at [:system "python3.6m"]
Nov 19, 2020 3:08:58 PM clojure.tools.logging$eval175$fn__178 invoke
INFO: Library c found at [:system "c"]
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Executing python initialize with options:{:python-executable nil, :program-name nil, :python-home nil, :library-path nil}
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Detecting startup-info for Python executable:
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Startup info detected: {:python-home "/home/user/miniconda3/envs/usr", :lib-version "3.6", :libname "python3.6m", :java-library-path-addendum "/home/user/miniconda3/envs/usr/lib"}
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Setting java library path: /home/user/miniconda3/envs/usr/lib:/home/user/catkin_ws/devel/lib:/opt/ros/melodic/lib:/usr/java/packages/lib:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Reference thread starting
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Library python3.6m found at [:system "python3.6m"]
Nov 19, 2020 3:09:02 PM clojure.tools.logging$eval147$fn__150 invoke
INFO: Library c found at [:system "c"]
Syntax error (NullPointerException) compiling at (/tmp/form-init6713682379458716776.clj:1:73).
null
Full report at:
/tmp/clojure-10025123200951564818.edn
Subprocess failed
REPL server launch timed out.
Full report:
{:clojure.main/message
"Syntax error (NullPointerException) compiling at (/tmp/form-init6713682379458716776.clj:1:73).\nnull\n",
:clojure.main/triage
{:clojure.error/phase :compile-syntax-check,
:clojure.error/line 1,
:clojure.error/column 73,
:clojure.error/source "form-init6713682379458716776.clj",
:clojure.error/path "/tmp/form-init6713682379458716776.clj",
:clojure.error/class java.lang.NullPointerException},
:clojure.main/trace
{:via
[{:type clojure.lang.Compiler$CompilerException,
:message
"Syntax error compiling at (/tmp/form-init6713682379458716776.clj:1:73).",
:data
{:clojure.error/phase :compile-syntax-check,
:clojure.error/line 1,
:clojure.error/column 73,
:clojure.error/source "/tmp/form-init6713682379458716776.clj"},
:at [clojure.lang.Compiler load "Compiler.java" 7648]}
{:type java.lang.ExceptionInInitializerError,
:at [java.lang.Class forName0 "Class.java" -2]}
{:type java.lang.NullPointerException,
:at [clojure.core$alias invokeStatic "core.clj" 4272]}],
:trace
[[clojure.core$alias invokeStatic "core.clj" 4272]
[clojure.core$load_lib invokeStatic "core.clj" 5958]
[clojure.core$load_lib doInvoke "core.clj" 5928]
[clojure.lang.RestFn applyTo "RestFn.java" 142]
[clojure.core$apply invokeStatic "core.clj" 667]
[clojure.core$load_libs invokeStatic "core.clj" 5985]
[clojure.core$load_libs doInvoke "core.clj" 5969]
[clojure.lang.RestFn applyTo "RestFn.java" 137]
[clojure.core$apply invokeStatic "core.clj" 667]
[clojure.core$require invokeStatic "core.clj" 6007]
[clojure.core$require doInvoke "core.clj" 6007]
[clojure.lang.RestFn invoke "RestFn.java" 436]
[proj.anchoring__init load nil 4]
[proj.anchoring__init <clinit> nil -1]
[java.lang.Class forName0 "Class.java" -2]
[java.lang.Class forName "Class.java" 398]
[clojure.lang.RT classForName "RT.java" 2211]
[clojure.lang.RT classForName "RT.java" 2220]
[clojure.lang.RT loadClassForName "RT.java" 2239]
[clojure.lang.RT load "RT.java" 449]
[clojure.lang.RT load "RT.java" 424]
[clojure.core$load$fn__6839 invoke "core.clj" 6126]
[clojure.core$load invokeStatic "core.clj" 6125]
[clojure.core$load doInvoke "core.clj" 6109]
[clojure.lang.RestFn invoke "RestFn.java" 408]
[proj.core__init load nil 47]
[proj.core__init <clinit> nil -1]
[java.lang.Class forName0 "Class.java" -2]
[java.lang.Class forName "Class.java" 398]
[clojure.lang.RT classForName "RT.java" 2211]
[clojure.lang.RT classForName "RT.java" 2220]
[clojure.lang.RT loadClassForName "RT.java" 2239]
[clojure.lang.RT load "RT.java" 449]
[clojure.lang.RT load "RT.java" 424]
[clojure.core$load$fn__6839 invoke "core.clj" 6126]
[clojure.core$load invokeStatic "core.clj" 6125]
[clojure.core$load doInvoke "core.clj" 6109]
[clojure.lang.RestFn invoke "RestFn.java" 408]
[clojure.core$load_one invokeStatic "core.clj" 5908]
[clojure.core$load_one invoke "core.clj" 5903]
[clojure.core$load_lib$fn__6780 invoke "core.clj" 5948]
[clojure.core$load_lib invokeStatic "core.clj" 5947]
[clojure.core$load_lib doInvoke "core.clj" 5928]
[clojure.lang.RestFn applyTo "RestFn.java" 142]
[clojure.core$apply invokeStatic "core.clj" 667]
[clojure.core$load_libs invokeStatic "core.clj" 5985]
[clojure.core$load_libs doInvoke "core.clj" 5969]
[clojure.lang.RestFn applyTo "RestFn.java" 137]
[clojure.core$apply invokeStatic "core.clj" 667]
[clojure.core$require invokeStatic "core.clj" 6007]
[clojure.core$require doInvoke "core.clj" 6007]
[clojure.lang.RestFn invoke "RestFn.java" 408]
[user$eval5 invokeStatic "form-init6713682379458716776.clj" 1]
[user$eval5 invoke "form-init6713682379458716776.clj" 1]
[clojure.lang.Compiler eval "Compiler.java" 7177]
[clojure.lang.Compiler eval "Compiler.java" 7166]
[clojure.lang.Compiler eval "Compiler.java" 7166]
[clojure.lang.Compiler load "Compiler.java" 7636]
[clojure.lang.Compiler loadFile "Compiler.java" 7574]
[clojure.main$load_script invokeStatic "main.clj" 475]
[clojure.main$init_opt invokeStatic "main.clj" 477]
[clojure.main$init_opt invoke "main.clj" 477]
[clojure.main$initialize invokeStatic "main.clj" 508]
[clojure.main$null_opt invokeStatic "main.clj" 542]
[clojure.main$null_opt invoke "main.clj" 539]
[clojure.main$main invokeStatic "main.clj" 664]
[clojure.main$main doInvoke "main.clj" 616]
[clojure.lang.RestFn applyTo "RestFn.java" 137]
[clojure.lang.Var applyTo "Var.java" 705]
[clojure.main main "main.java" 40]],
:phase :compile-syntax-check}}