fix shader error report

src/gfx.ts

@@ -236,11 +236,9 @@ export class Shader {
 
 		if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
 			const vertError = gl.getShaderInfoLog(vertShader)
+			if (vertError) throw new Error("VERTEX SHADER " + vertError)
 			const fragError = gl.getShaderInfoLog(fragShader)
-			let msg = ""
-			if (vertError) msg += vertError
-			if (fragError) msg += fragError
-			throw new Error(msg)
+			if (fragError) throw new Error("FRAGMENT SHADER " + fragError)
 		}
 
 		gl.deleteShader(vertShader)

src/kaboom.ts

@@ -1369,7 +1369,17 @@ export default (gopt: KaboomOpt = {}): KaboomCtx => {
 	): Shader {
 		const vcode = VERT_TEMPLATE.replace("{{user}}", vertSrc ?? DEF_VERT)
 		const fcode = FRAG_TEMPLATE.replace("{{user}}", fragSrc ?? DEF_FRAG)
-		return new Shader(ggl, vcode, fcode, VERTEX_FORMAT.map((vert) => vert.name))
+		try {
+			return new Shader(ggl, vcode, fcode, VERTEX_FORMAT.map((vert) => vert.name))
+		} catch (e) {
+			const lineOffset = 14
+			const fmtRegex = /(?<type>^\w+) SHADER ERROR: 0:(?<line>\d+): (?<msg>.+)/
+			const match = (e as Error).message.match(fmtRegex)
+			const line = Number(match.groups.line) - lineOffset
+			const msg = match.groups.msg.trim()
+			const ty = match.groups.type.toLowerCase()
+			throw new Error(`${ty} shader line ${line}: ${msg}`)
+		}
 	}
 
 	function makeFont(