Add new Gatsby template

Author: jlyonsmith

Diff for: catalog.json5

@@ -1,14 +1,22 @@
 {
-  "js-package-template": {
+  "js-package": {
     description: "JS package template",
     url: "https://github.com/jlyonsmith/js-package-template.git",
   },
-  "node-cli-tool-template": {
+  "node-cli": {
     description: "Node CLI tool template",
     url: "https://github.com/jlyonsmith/node-cli-tool-template.git",
   },
-  "phaser-template": {
+  "node-ts-cli": {
+    description: "Node/TypeScript CLI template",
+    url: "https://github.com/jlyonsmith/node-ts-cli-template.git",
+  },
+  phaser: {
     description: "Phaser game template",
     url: "https://github.com/jlyonsmith/phaser-template.git",
   },
+  "gatsby-mui": {
+    description: "Gatsby with Material-UI template",
+    url: "https://github.com/jlyonsmith/gatsby-mui-template.git",
+  },
 }

Diff for: src/GitExtraTool.ts

@@ -52,14 +52,14 @@ export class GitExtraTool {
     this.debug = options.debug
   }
 
-  async ensureCommands(cmds) {
+  async ensureCommands(cmds): Promise<void> {
     this.cmds = this.cmds || new Set()
 
     const newCmds = cmds.filter((cmd) => !this.cmds.has(cmd))
     const exists = await Promise.all(newCmds.map((cmd) => commandExists(cmd)))
 
     newCmds.forEach((cmd) => {
-      if (!!exists[cmd]) {
+      if (exists[cmd]) {
         throw new Error(`Command '${cmd}' does not exist. Please install it.`)
       } else {
         this.cmds.add(cmd)