Breaks upstream TypeScriptLexer by mutating pygments.lexers.javascript.JavascriptLexer.tokens

[andersk]

Here’s the upstream Pygments TypeScriptLexer working as normal:

$ python
Python 3.8.10 (default, Mar 13 2023, 10:26:41) 
[GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pygments, pygments.lexers
>>> print(*pygments.lex("let m: Map<K, V>;", pygments.lexers.TypeScriptLexer()), sep='\n')
(Token.Keyword.Declaration, 'let')
(Token.Text.Whitespace, ' ')
(Token.Name.Other, 'm')
(Token.Operator, ':')
(Token.Text.Whitespace, ' ')
(Token.Keyword.Type, 'Map')
(Token.Operator, '<')
(Token.Name.Other, 'K')
(Token.Punctuation, ',')
(Token.Text.Whitespace, ' ')
(Token.Name.Other, 'V')
(Token.Operator, '>')
(Token.Punctuation, ';')
(Token.Text.Whitespace, '\n')

But if I start a new Python process and instead import jsx before the first time I use TypeScriptLexer, TypeScriptLexer incorrectly produces Token.Error tokens:

$ python
Python 3.8.10 (default, Mar 13 2023, 10:26:41) 
[GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pygments, pygments.lexers, jsx
>>> print(*pygments.lex("let m: Map<K, V>;", pygments.lexers.TypeScriptLexer()), sep='\n')
(Token.Keyword.Declaration, 'let')
(Token.Text.Whitespace, ' ')
(Token.Name.Other, 'm')
(Token.Operator, ':')
(Token.Text.Whitespace, ' ')
(Token.Keyword.Type, 'Map')
(Token.Punctuation, '<')
(Token.Name.Tag, 'K')
(Token.Error, ',')
(Token.Text, ' ')
(Token.Name.Attribute, 'V')
(Token.Punctuation, '>')
(Token.Punctuation, ';')
(Token.Text.Whitespace, '\n')

This is because jsx-lexer destructively mutates pygments.lexers.javascript.JavascriptLexer.tokens which doesn’t belong to it:

jsx-lexer/jsx/lexer.py

Lines 8 to 9 in 5d764e7

	TOKENS = JavascriptLexer.tokens
	TOKENS.update(