Fix source files to adhere to stricter TS type checking

src/connect.ts

@@ -147,6 +147,10 @@ export async function createSocket(config: FileSystemConfig): Promise<NodeJS.Rea
           Logging.debug(`\tError connecting to hop ${config.hop} for ${config.name}: ${err}`);
           err.message = `Couldn't connect through the hop:\n${err.message}`;
           return reject(err);
+        } else if (!channel) {
+          err = new Error('Did not receive a channel');
+          Logging.debug(`\tGot no channel when connecting to hop ${config.hop} for ${config.name}`);
+          return reject(err);
         }
         channel.once('close', () => ssh.destroy());
         resolve(channel);

src/sshFileSystem.ts

@@ -26,7 +26,7 @@ export class SSHFileSystem implements vscode.FileSystemProvider {
     if (relPath.startsWith('/')) relPath = relPath.substr(1);
     return path.posix.resolve(this.root, relPath);
   }
-  public continuePromise<T>(func: (cb: (err: Error | null, res?: T) => void) => boolean): Promise<T> {
+  public continuePromise<T>(func: (cb: (err: Error | null | undefined, res?: T) => void) => boolean): Promise<T> {
     return new Promise<T>((resolve, reject) => {
       const exec = () => {
         this.waitForContinue = false;

src/toPromise.ts

@@ -1,5 +1,5 @@
 
-export type toPromiseCallback<T> = (err: Error | null, res?: T) => void;
+export type toPromiseCallback<T> = (err: Error | null | undefined, res?: T) => void;
 export async function toPromise<T>(func: (cb: toPromiseCallback<T>) => void): Promise<T> {
   return new Promise<T>((resolve, reject) => {
     try {

webview/src/FieldTypes/base.tsx

@@ -50,7 +50,7 @@ export abstract class FieldBase<T, P = {}, S = {}> extends React.Component<Props
         }
         return validator ? validator(newValue!) : null;
     }
-    public getValue(): T {
+    public getValue(): T | undefined {
         const { newValue, oldValue } = this.state;
         if (newValue === undefined) {
             return this.props.optional ? newValue : oldValue;

webview/src/FieldTypes/dropdown.tsx

@@ -23,7 +23,7 @@ export class FieldDropdown<T> extends FieldBase<T, Props<T>, State<T>> {
     public renderInput() {
         const { newValue, open } = this.state;
         const { displayName } = this.props;
-        const display = newValue ? (displayName ? displayName(newValue) : newValue.toString()) : '';
+        const display = newValue ? (displayName ? displayName(newValue) : `${newValue}`) : '';
         return <div className="FieldDropdown" ref={this.mainDivRef}>
             <p style={{ float: 'right', margin: 5 }}>▼</p>
             <div className="current" onClick={this.toggle}>{display}</div>
@@ -35,7 +35,7 @@ export class FieldDropdown<T> extends FieldBase<T, Props<T>, State<T>> {
         const generateItem = (item: T, index: number) => {
             const style = displayStyle && displayStyle(item);
             return <li key={index} style={style} onClick={this.select.bind(this, item)}>
-                {displayName ? displayName(item) : item.toString()}
+                {displayName ? displayName(item) : `${item}`}
             </li>
         };
         return <ul className="list">