fix(ci): reject empty LCOV source paths

Author: roomote

src/scripts/verify-lcov.mjs

@@ -11,6 +11,7 @@ export function verifyLcov(content) {
 	for (const line of content.split(/\r?\n/)) {
 		if (line.startsWith("SF:")) {
 			if (inRecord) throw new Error("LCOV source record is not terminated")
+			if (!line.slice(3)) throw new Error("LCOV source path is empty")
 			inRecord = true
 			linesFound = undefined
 			linesHit = undefined

src/scripts/verify-lcov.spec.mjs

@@ -8,6 +8,7 @@ describe("verifyLcov", () => {
 	})
 
 	it.each([
+		["an empty source path", "SF:\nLF:1\nLH:1\nend_of_record\n"],
 		["an unterminated record", "SF:file.ts\nLH:1\n"],
 		["a zero-hit report", "SF:file.ts\nLF:1\nLH:0\nend_of_record\n"],
 		["a hit count outside a record", "LH:1\n"],