fix: webpackCompilerService should not cache childProcesses forever

Currently the webpackCompilerService caches the started webpack processes, but it removes them from the cache only when someone calls `stopWebpackCompiler` method.
This is a major problem as we cache the first instance of the child process and we do not remove it, even when the process dies. For example, when you run just build, we start the webpack process without watch mode, the webpackCompilerService caches the child process, it exits, but the instance remains cached.
Trying to run the application on device does not start new webpack process and different failures occur.

Author: rosen-vladimirov

lib/services/webpack/webpack-compiler-service.ts

@@ -72,6 +72,7 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 
 			childProcess.on("error", (err) => {
 				this.$logger.trace(`Unable to start webpack process in watch mode. Error is: ${err}`);
+				delete this.webpackProcesses[platformData.platformNameLowerCase];
 				reject(err);
 			});
 
@@ -82,6 +83,7 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 				this.$logger.trace(`Webpack process exited with code ${exitCode} when we expected it to be long living with watch.`);
 				const error = new Error(`Executing webpack failed with exit code ${exitCode}.`);
 				error.code = exitCode;
+				delete this.webpackProcesses[platformData.platformNameLowerCase];
 				reject(error);
 			});
 		});
@@ -97,12 +99,14 @@ export class WebpackCompilerService extends EventEmitter implements IWebpackComp
 			const childProcess = await this.startWebpackProcess(platformData, projectData, prepareData);
 			childProcess.on("error", (err) => {
 				this.$logger.trace(`Unable to start webpack process in non-watch mode. Error is: ${err}`);
+				delete this.webpackProcesses[platformData.platformNameLowerCase];
 				reject(err);
 			});
 
 			childProcess.on("close", async (arg: any) => {
 				await this.$cleanupService.removeKillProcess(childProcess.pid.toString());
 
+				delete this.webpackProcesses[platformData.platformNameLowerCase];
 				const exitCode = typeof arg === "number" ? arg : arg && arg.code;
 				if (exitCode === 0) {
 					resolve();