Error when checking LaTeX documents ending with specific commands

[JSchmiegel]

Describe the bug
I am currently working on my bachelor thesis. Unfortunately I have the problem that one of my LaTeX documents is not checked by the Ltex plugin. After a bit of trial and error, I think I can reduce the problem to the command \cites{test}.
But strangely enough, this does not apply to all LaTeX documents in which I have the \cites{} command. But if I use an empty LaTeX document only with the content \cites{test}, then I get the error. Very strange!

Please give me feedback if anyone can reproduce this error.

Steps to reproduce

1. Use a blank .tex file with \cites{test}
2. Try to run the LTeX: Check Current Document Command

Expected behavior
Normal marking of spelling mistakes by LTeX.

LTeX configuration

{
    "ltex.additionalRules.motherTongue": "de-DE",
    "ltex.language": "de-DE",
    "ltex.sentenceCacheSize": 50000,
    "ltex.java.maximumHeapSize": 8192
}

"LTeX Language Server" log file

[Info  - 12:29:10 PM] Starting ltex-ls...
Jul 03, 2021 12:29:11 PM org.bsplines.ltexls.server.LtexLanguageServer initialize
INFO: ltex-ls 12.2.0 - initializing...
Jul 03, 2021 12:29:11 PM org.bsplines.ltexls.server.LtexLanguageServer initialize
INFO: Setting locale to 'en'
Jul 03, 2021 12:29:11 PM org.bsplines.ltexls.settings.SettingsManager logDifferentSettings
FINE: Reinitializing LanguageTool due to different settings for language 'de-DE': setting 'settings', old 'null', new 'non-null'
Jul 03, 2021 12:29:18 PM org.eclipse.lsp4j.jsonrpc.RemoteEndpoint fallbackResponseError
SEVERE: Internal error: java.lang.StringIndexOutOfBoundsException: String index out of range: 12
java.util.concurrent.CompletionException: java.lang.StringIndexOutOfBoundsException: String index out of range: 12
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:645)
	at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
	at java.base/java.lang.Thread.run(Thread.java:831)
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: 12
	at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:48)
	at java.base/java.lang.String.charAt(String.java:711)
	at org.bsplines.ltexls.parsing.latex.LatexCommandSignature.matchArgumentFromPosition(LatexCommandSignature.java:135)
	at org.bsplines.ltexls.parsing.latex.LatexCommandSignature.matchFromPosition(LatexCommandSignature.java:219)
	at org.bsplines.ltexls.parsing.latex.LatexCommandSignature.matchFromPosition(LatexCommandSignature.java:204)
	at org.bsplines.ltexls.parsing.latex.LatexAnnotatedTextBuilder.processBackslash(LatexAnnotatedTextBuilder.java:600)
	at org.bsplines.ltexls.parsing.latex.LatexAnnotatedTextBuilder.addCode(LatexAnnotatedTextBuilder.java:309)
	at org.bsplines.ltexls.parsing.latex.LatexAnnotatedTextBuilder.addCode(LatexAnnotatedTextBuilder.java:30)
	at org.bsplines.ltexls.server.DocumentChecker.buildAnnotatedTextFragments(DocumentChecker.java:64)
	at org.bsplines.ltexls.server.DocumentChecker.check(DocumentChecker.java:215)
	at org.bsplines.ltexls.server.LtexTextDocumentItem.check(LtexTextDocumentItem.java:466)
	at org.bsplines.ltexls.server.LtexTextDocumentItem.checkAndGetDiagnostics(LtexTextDocumentItem.java:342)
	at org.bsplines.ltexls.server.LtexTextDocumentItem.checkAndPublishDiagnostics(LtexTextDocumentItem.java:319)
	at org.bsplines.ltexls.server.LtexTextDocumentItem.checkAndPublishDiagnosticsWithoutCache(LtexTextDocumentItem.java:313)
	at org.bsplines.ltexls.server.LtexWorkspaceService.lambda$executeCheckDocumentCommand$2(LtexWorkspaceService.java:156)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:642)
	... 7 more

"LTeX Language Client" log file

2021-07-03T10:29:09.875Z Info: Setting LTeX UI language to 'en-us'.
2021-07-03T10:29:09.876Z Info: Loading i18n messages...
2021-07-03T10:29:09.876Z Info: Loading default i18n messages...
2021-07-03T10:29:09.877Z Info: 
2021-07-03T10:29:09.877Z Info: ltex.ltex-ls.path not set.
2021-07-03T10:29:09.877Z Info: Searching for ltex-ls in '/home/jonas/.vscode/extensions/valentjn.vscode-ltex-10.4.0/lib'...
2021-07-03T10:29:09.878Z Info: ltex-ls found in '/home/jonas/.vscode/extensions/valentjn.vscode-ltex-10.4.0/lib/ltex-ls-12.2.0'.
2021-07-03T10:29:09.878Z Info: 
2021-07-03T10:29:09.878Z Info: ltex.java.path not set.
2021-07-03T10:29:09.878Z Info: Using ltex-ls from '/home/jonas/.vscode/extensions/valentjn.vscode-ltex-10.4.0/lib/ltex-ls-12.2.0'.
2021-07-03T10:29:09.878Z Info: Using Java from PATH or JAVA_HOME (may fail if not installed).
2021-07-03T10:29:09.888Z Info: Testing ltex-ls...
2021-07-03T10:29:09.888Z Info:   Command: "/home/jonas/.vscode/extensions/valentjn.vscode-ltex-10.4.0/lib/ltex-ls-12.2.0/bin/ltex-ls"
2021-07-03T10:29:09.888Z Info:   Arguments: ["--version"]
2021-07-03T10:29:09.888Z Info:   env['JAVA_HOME']: undefined
2021-07-03T10:29:09.888Z Info:   env['JAVA_OPTS']: "-Xms64m -Xmx8192m"
2021-07-03T10:29:10.141Z Info: Test successful!
2021-07-03T10:29:10.142Z Info: 
2021-07-03T10:29:10.144Z Info: Starting ltex-ls...
2021-07-03T10:29:10.144Z Info:   Command: "/home/jonas/.vscode/extensions/valentjn.vscode-ltex-10.4.0/lib/ltex-ls-12.2.0/bin/ltex-ls"
2021-07-03T10:29:10.144Z Info:   Arguments: []
2021-07-03T10:29:10.144Z Info:   env['JAVA_HOME']: undefined
2021-07-03T10:29:10.144Z Info:   env['JAVA_OPTS']: "-Xms64m -Xmx8192m"
2021-07-03T10:29:10.144Z Info: 

Version information

• Operating system: Linux (Fedora/34 Kernel: 5.12.12-300-fc34-x86_)
• VS Code: 1.57.1
• vscode-ltex: v10.4.0

[valentjn]

Thanks for the report. FWIW, the error occurred when the document ends with specific commands (like \cites{...}) without any final newline.

[valentjn]

Fix released in 10.5.0.