Confusing error expected pattern, found... in let-bindings

[Leedehai]

Description

Since release 0.11, context is a new reserved keyword, but if an unwitting user wants to define a variable named context, the error message is confusing:

#let context = 1 + 2
// actual error: 1:6-1:13 expected pattern, found `context` expression
// I suggest:    1:6-1:13 expected identifier name, found keyword `context`

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Similar but different, because the error highlighted the entire let = 1 + 2 part, not just the second let word:

#let let = 1 + 2
// actual error: 1:6-1:17 expected pattern, found `let` expression
// I suggest:    1:6-1:9 expected identifier name, found keyword `let`

Note the highlighted span (1:6-1:17) let = 1 + 2 is actually not a valid "let expression" either -- it's missing the identifier.

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Okay-ish because it says as is a keyword and there's an hint, but the word "pattern" here is still confusing to users. Note it does not refer to Typst's pattern type.

#let as = 1 + 2
// actual output:
// Error: 1:6-1:8 expected pattern, found keyword `as`
// Hint: 1:6-1:8 keyword `as` is not allowed as an identifier; try `as_` instead

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Typst thrives on clear error messages (much clearer than LaTeX :) ), so I think it's worth improvement in these cases.

Reproduction URL

No response

Operating system

Web app, Windows, Linux, macOS

Typst version

• I am using the latest version of Typst