module
   position
   header
   ... 

and, like always, javascript demands a trailing comma on lines when there are more lines following… (comma means more to follow)

config: {
				weatherProvider: "openmeteo",
				appendLocationNameToHeader: false, //<---add comma
				type: "current",
				lat: 51.12345 //<--- missing comma (there is more to follow this line)
				lon: -0.12345
			}

@sdetweil said:

appendLocationToHeader

			module: "weather",
			---->appendLocationNameToHeader: false
			//header: 'Current My_City weather: ',	
			position: "top_right",
			config: {
				weatherProvider: "openmeteo",
				----> appendLocationNameToHeader: false
				type: "current",
				lat: 51.12345
				lon: -0.12345
			}

Spelling shown in docs is appendLocationNameToHeader
Neither of the two position above work, mirror fails to load.

appendLocationToHeader

Set it to false,

Check the spelling in the module documentation