fix: prevent TypeAssertionError panic when filetype setting is non-string (issue #4042)#4043
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When saving a file to a new path (newPath=true), ReloadSettings is called
with reloadFiletype=true. If the user config contains a glob or ft: block
that somehow places a non-string value under the 'filetype' key (e.g. a
map[string]interface{} from a nested config entry), the unchecked type
assertions b.Settings["filetype"].(string) panic at runtime.
This was reproducible with kitty+nushell (issue micro-editor#4042):
$ micro → CTRL-s → f → crash
Fixes:
- Add a settingAsString helper in settings.go that safely converts
a settings value to string, falling back to a default on type mismatch
- Replace all bare .(string) assertions on b.Settings["filetype"] in
buffer.go (UpdateRules, FileType, buffer init) and settings.go
(ReloadSettings) with settingAsString calls
- In ReloadSettings, only assign settings["filetype"] to b.Settings if
the value is actually a string, silently ignoring non-string values
Fixes micro-editor#4042
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Andriamanitra
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Andriamanitra
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I don't think this is fixing the root cause of the problem. Instead of allowing nonsensical values for settings we should reject them in validateParsedSettings.
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Summary
Fixes #4042 —
Crash when savingwith kitty+nushell.Reproduction:
Root Cause
When saving a file to a new path (
newPath=true),buffer.ReloadSettings(true)is called. The function reads the parsed config and callsUpdatePathGlobLocals, which may populatesettings["filetype"]with amap[string]interface{}value (from a glob-based config block) instead of a plain string.The subsequent bare type assertion
b.Settings["filetype"].(string)then panics. The same issue exists inUpdateRules(),FileType(), and the buffer initialisation path.Fix
settingAsString(v any, defaultVal string) stringhelper insettings.gothat safely converts a settings value to string, falling back to a safe default on type mismatch..(string)assertions onb.Settings["filetype"]inbuffer.goandsettings.gowithsettingAsStringcalls.ReloadSettings, added an explicit type guard when assigning from parsed settings — non-stringfiletypevalues are silently ignored (the value stays"unknown", which letsUpdateRulespick the right filetype by extension).Testing
go build ./...passes ✅go test ./internal/buffer/...— all 14 tests pass ✅Files Changed
internal/buffer/settings.go— helper + safe assertions inReloadSettingsinternal/buffer/buffer.go— safe assertions inUpdateRules,FileType, buffer init