Cannot remove 'files.associations' preferences

[saltylassi]

Bug Description:

when remove files.associations for custom preferences editor widget, error occurs at FileSystemFrontendContribution.updateAssociations

- FileSystemFrontendContribution

    protected updateAssociations(): void {
        const fileAssociations = this.preferences['files.associations'];
        const mimeAssociations = Object.keys(fileAssociations).map(filepattern => ({ id: fileAssociations[filepattern], filepattern }));
        this.mimeService.setAssociations(mimeAssociations);
    }

this.preferences['files.associations'] becomes undefined, and Object.keys(undefined) makes error.

here is my code:

function removePreferences(rebind: interfaces.Rebind, contrib: interfaces.ServiceIdentifier<unknown>, sch: PreferenceSchema): void {
    rebind(contrib).toConstantValue({
        schema: (() => {
            const s = sch;
            const schemaKeys = Object.keys(s.properties);
            schemaKeys.forEach(key => {
                delete s.properties[key];
            });

            return s;
        })()
    });

removePreferences(rebind, FileSystemPreferenceContribution, filesystemPreferenceSchema);

c5a7d71#diff-f36fb1a0e913ea06a31998757f31c1f5a1841dd8ee33352257c9beb89771b818

I know file extension is necessary for checking language type, but that error annoys me. sorry

Steps to Reproduce:

1. remove files.associations
2. Uncaught TypeError TypeError: Cannot convert undefined or null to object

Additional Information

• Operating System: Windows10
• Theia Version: 1.29

[vince-fugnitto]

I know file extension is necessary for checking language type, but that error annoys me. sorry

@saltylassi thank you for reporting the issue, I'm not entirely convinced it is a bug but if you're not interested in files.associtations (where you completely remove the preference) you can always override updateAssociations in your application.