Fix crash for \begin/\end without argument

Fixes valentjn/vscode-ltex#236.
me-johnomar · Jan 27, 2021 · 24c99df · 24c99df
1 parent b4509e4
commit 24c99df
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -16,6 +16,7 @@
 - Disable `UPPERCASE_SENTENCE_START` in BibT<sub>E</sub>X files (see [vscode-ltex#211](https://github.com/valentjn/vscode-ltex/issues/211))
 - Move rule ID to the end of diagnostic messages as VS Code truncates the messages if the Problems panel is narrow (fixes [vscode-ltex#233](https://github.com/valentjn/vscode-ltex/issues/233))
 - Fix regression that messages of possible spelling mistakes are not prepended with the respective unknown words (see [vscode-ltex#161](https://github.com/valentjn/vscode-ltex/issues/161))
+- Fix crash when using `\begin` or `\end` without an argument (fixes [vscode-ltex#236](https://github.com/valentjn/vscode-ltex/issues/236))
 
 ## 9.1.0 (January 24, 2021)
 

diff --git a/ltexls-core/src/main/java/org/bsplines/ltexls/parsing/latex/LatexAnnotatedTextBuilder.java b/ltexls-core/src/main/java/org/bsplines/ltexls/parsing/latex/LatexAnnotatedTextBuilder.java
@@ -507,7 +507,8 @@ public LatexAnnotatedTextBuilder addCode(String code) {
               addMarkup(command);
 
               String argument = matchFromPosition(argumentPattern);
-              String environmentName = argument.substring(1, argument.length() - 1);
+              String environmentName = ((argument.length() >= 2)
+                  ? argument.substring(1, argument.length() - 1) : "");
               String interpretAs = "";
 
               if (mathEnvironments.contains(environmentName)) {