[INTERNAL] Fix missing peerDependency to acorn / Add CI check

Due to a bug in npm, acorn-jsx can't find the correct version of acorn.

Downgrading to [email protected] solves the issue as only one acorn version (v7) is present.

Also adding an 'npm ls' check to detect such issues before they get merged into master.

Author: matz3

azure-pipelines.yml

@@ -36,6 +36,9 @@ steps:
 - script: npm ci
   displayName: Install Dependencies
 
+- script: npm ls
+  displayName: Check for missing / extraneous Dependencies
+
 - script: npm run test-azure
   displayName: Run Tests
 

package-lock.json

@@ -125,7 +125,7 @@
 	},
 	"devDependencies": {
 		"@ui5/project": "^2.2.0",
-		"ava": "^3.12.1",
+		"ava": "3.11.1",
 		"chokidar-cli": "^2.1.0",
 		"coveralls": "^3.1.0",
 		"cross-env": "^7.0.2",