Bug fix on ipfs validation for studio (#761)

* compiler: Remove 'async' from function that should be syncronous

Without this, the thrown error by the function would happen on the
`UNCAUGHT EXCEPTION` log, which is unwanted, since we want this to
block the hole compilation step.

* compiler: Use absolute file path for ipfs validation

Without this the CLI would break trying to open the mapping
file using the relative path, that only works when passing to
the AS compiler.

Eg: Error: Failed to compile data source mapping: ENOENT: no such file or directory, open '../src/xxxx.ts'

* 0.22.4

Author: evaporei

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@graphprotocol/graph-cli",
-  "version": "0.22.3",
+  "version": "0.22.4",
   "description": "CLI for building for and deploying to The Graph",
   "dependencies": {
     "assemblyscript": "0.19.10",

src/compiler/index.js

@@ -243,7 +243,7 @@ class Compiler {
       let baseDir = this.sourceDir
       let absoluteMappingPath = path.resolve(baseDir, mappingPath)
       let inputFile = path.relative(baseDir, absoluteMappingPath)
-      this._validateMappingContent(inputFile)
+      this._validateMappingContent(absoluteMappingPath)
 
       // If the file has already been compiled elsewhere, just use that output
       // file and return early
@@ -308,7 +308,7 @@ class Compiler {
       let baseDir = this.sourceDir
       let absoluteMappingPath = path.resolve(baseDir, mappingPath)
       let inputFile = path.relative(baseDir, absoluteMappingPath)
-      this._validateMappingContent(inputFile)
+      this._validateMappingContent(absoluteMappingPath)
 
       // If the file has already been compiled elsewhere, just use that output
       // file and return early
@@ -368,7 +368,7 @@ class Compiler {
     }
   }
 
-  async _validateMappingContent(filePath) {
+  _validateMappingContent(filePath) {
     const data = fs.readFileSync(filePath)
     if (
       this.blockIpfsMethods &&