raise error for unknown compiler version

packages/sol-compiler/src/compiler.ts

@@ -85,6 +85,9 @@ export class Compiler {
     private static async _getSolcAsync(
         solcVersion: string,
     ): Promise<{ solcInstance: solc.SolcInstance; fullSolcVersion: string }> {
+        if (_.isUndefined(binPaths[solcVersion])) {
+            throw new Error(`${solcVersion} is not a known compiler version`);
+        }
         const fullSolcVersion = binPaths[solcVersion];
         const compilerBinFilename = path.join(SOLC_BIN_DIR, fullSolcVersion);
         let solcjs: string;