message: Fix environment completion
  This closes
diff: @@ -6,8 +6,8 @@ import {Extension} from '../../main'
  export class Environment {
  extension: Extension
  - private defaultEnvs: vscode.CompletionItem[]
  - private packageEnvs: {[pkg: string]: vscode.CompletionItem[]}
  + private defaultEnvs: vscode.CompletionItem[] = []
  + private packageEnvs: {[pkg: string]: vscode.CompletionItem[]} = {}
  constructor(extension: Extension) {
  this.extension = extension
  