[INTERNAL] ESLint: All promise rejection reasons must be an Error

eslint-config-google 0.12.0 makes this an error

Also fix async functions resolving to promises rejecting with errors.
Async functions should better directly reject with errors.

test/lib/lbt/analyzer/ComponentAnalyzer.js

@@ -372,7 +372,9 @@ test("analyze: without manifest", async (t) => {
 	const mockPool = {
 		async findResource() {
 			return {
-				buffer: async () => Promise.reject()
+				buffer: async () => {
+					throw new Error("Some error");
+				}
 			};
 		}
 	};

test/lib/lbt/analyzer/FioriElementsAnalyzer.js

@@ -16,7 +16,9 @@ test("analyze: without manifest", async (t) => {
 	const mockPool = {
 		async findResource() {
 			return {
-				buffer: async () => Promise.reject()
+				buffer: async () => {
+					throw new Error("Some error");
+				}
 			};
 		}
 	};

test/lib/lbt/analyzer/SmartTemplateAnalyzer.js

@@ -18,7 +18,9 @@ test("analyze: without manifest", async (t) => {
 	const mockPool = {
 		async findResource() {
 			return {
-				buffer: async () => Promise.reject()
+				buffer: async () => {
+					throw new Error("Some error");
+				}
 			};
 		}
 	};

test/lib/lbt/graph/dependencyGraph.js

@@ -123,7 +123,7 @@ test("dependency with 2 roots", async (t) => {
 test("dependency graph with rejecting pool", async (t) => {
 	const pool = {
 		async getModuleInfo() {
-			return Promise.reject("myerror");
+			throw new Error("myerror");
 		}
 	};
 	const roots = [{

test/lib/lbt/resources/ResourcePool.js

@@ -61,7 +61,7 @@ test("resources", async (t) => {
 
 class ResourcePoolWithRejectingModuleInfo extends ResourcePool {
 	async getModuleInfo(name) {
-		return Promise.reject("myerror");
+		throw new Error("myerror");
 	}
 }