message: explicit plug builder typing
diff: @@ -531,7 +531,7 @@ function buildCachedDimPlugSet(defs: D2ManifestDefinitions, plugSetHash: number)
  /**
  * This builds DimPlugs and caches their values so we reduce the number of instances in memory.
  */
  -function buildCachedDefinedPlug(defs: D2ManifestDefinitions, plugHash: number) {
  +function buildCachedDefinedPlug(defs: D2ManifestDefinitions, plugHash: number): DimPlug | null {
  const cachedValue = definedPlugCache[plugHash];
  // The result of buildDefinedPlug can be null, we still consider that a cached value.
  if (cachedValue !== undefined) {
  