fix(gnolang): fix an indexExpr preprocess bug

[ltzmaxwell]

Description

type assertion to *MapType may fail while preprocessing *IndexExpr, it may cause a v, ok := Values[k] operation fail especially when it's declared like type Values map[string][]string, detailed in map28c.gno test.

How has this been tested?

passed.

[zivkovicmilos]

Hey @ltzmaxwell,

Thank you for the contribution 🙏

Can you please give me an example of when this *MapType assertion might fail?

[thehowl]

rest looks good to me

(as an aside, I don't understand why we have files almost exactly matching files2 if the tests are executed in the same way, but that belongs to another issue)

[moul]

rest looks good to me

(as an aside, I don't understand why we have files almost exactly matching files2 if the tests are executed in the same way, but that belongs to another issue)

Let me add info about this point in the files/README.md file.

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Edit: I just checked and the information is already there.

The difference is:

• files uses ImportModeNativePreferred
• files2 uses ImportModeStdlibsPreferred

See: https://github.com/gnolang/gno/blob/master/tests/imports.go#L61-L63

By default, we should try to put the tests on both folders.

[moul]

Let’s merge, and wait for a make fmt to happen in another PR, or that someone updates the CI to include tests/ files.

[thehowl]

The difference is:

files uses ImportModeNativePreferred
files2 uses ImportModeStdlibsPreferred

Missed that. Still think we could make this better, but will make a proposal in a pr