Fix parser translator tokens for comment-only file

Earlopain · Earlopain · commit 4d0851cb0f31 · 2025-01-12T13:56:11.000+01:00
In #3393 I made a mistake. When there is no previous token, it wraps around to -1. Oops
diff --git a/lib/prism/translation/parser/lexer.rb b/lib/prism/translation/parser/lexer.rb
@@ -284,10 +284,10 @@ def to_a
                 value.chomp!
                 location = range(token.location.start_offset, token.location.end_offset - 1)
 
-                prev_token = lexed[index - 2][0]
+                prev_token = lexed[index - 2][0] if index - 2 >= 0
                 next_token = lexed[index][0]
 
-                is_inline_comment = prev_token.location.start_line == token.location.start_line
+                is_inline_comment = prev_token&.location&.start_line == token.location.start_line
                 if is_inline_comment && !COMMENT_CONTINUATION_TYPES.include?(next_token&.type)
                   tokens << [:tCOMMENT, [value, location]]
 
diff --git a/test/prism/fixtures/comment_single.txt b/test/prism/fixtures/comment_single.txt
@@ -0,0 +1 @@
+# Foo
diff --git a/test/prism/snapshots/comment_single.txt b/test/prism/snapshots/comment_single.txt
