fix(language-service): prevent crash on malformed html.customData configuration

[WangKepeople]

Description

Fixes a server crash (TypeError: paths is not iterable) when an LSP client returns an array containing null elements (e.g., [null]) for the unconfigured html.customData option.

Context

Some non-VS Code LSP clients (such as Emacs Eglot) respond to workspace/configuration requests with [null] when a configuration section is not explicitly set in the workspace settings.

Currently, (await context.env.getConfiguration?.("html.customData")) ?? [] evaluates to [null] (since [null] is truthy), causing the subsequent for (const path of paths) loop to assign null to path and throw a runtime error inside getCustomData().

Changes

• Safely check and filter out null or falsy items from the html.customData array using Array.isArray(rawPaths) ? rawPaths.filter(Boolean) : [].

[KazariEX]

The error report seems to indicate that paths itself is not iterable. If it were [null], it should not produce TypeError: paths is not iterable.