Making a really dumb Ionic 3 Filelogger

app.component.ts

constructor(platform: Platform) {

    platform
      .ready()
      .then(() => {
        // statusBar.overlaysWebView(false);
        statusBar.styleDefault();
        splashScreen.hide();

        this.dumblog.realLog = console;

        // Override console cause we're nuts.
        console = <any> this.dumblog;

        this.init();
      });
}

stupid-filelog.ts

import { Injectable } from '@angular/core';
import { File } from '@ionic-native/file';

import * as moment from 'moment';
import { Platform } from 'ionic-angular';

@Injectable()
export class StupidFilelog {
  localConsole: Console;
  fileCreated: boolean;
  isWriting: boolean;

  constructor(private file: File, private platform: Platform) {
    // super();
  }

  public set realLog(log: Console) {
    this.localConsole = log;
  }

  public log(...messages) {
    this.writeToLogfile('log', messages);
  }

  public warn(...message) {
    this.writeToLogfile('warn', message);
  }

  public info(...message) {
    this.writeToLogfile('info', message);
  }

  public error(...message) {
    this.writeToLogfile('error', message);
  }

  private getLogfileDir(): string {
    if (this.platform.is('ios')) {
      return this.file.documentsDirectory;
    }

    return this.file.dataDirectory + '/Documents';
  }

  private createFileIfNotExists() {
    if (this.fileCreated) {
      return;
    }

    this.fileCreated = true;
    this.isWriting = true;
    this.file.createFile(this.getLogfileDir(), 'consolelog.log', false)
      .then(() => {this.isWriting = false; this.localConsole.log('Created logfile.')})
      .catch((e: Error) => {this.isWriting = false; this.localConsole.log('Failed to create logfile.'); this.localConsole.log(e.toString())});
  }

  protected writeToLogfile(level, messages: any[]) {
    this.createFileIfNotExists();
    messages.forEach((message) => {
      if (!this.platform.is('cordova')) {
        return this.localConsole[level](message);
      }

      try {
        message = JSON.stringify(message).substr(0, 500);
      } catch (e) {
        message = 'LOG Omitted - cyclical JSON.';
      }

      const timestamp = moment().format();
      const line = `${timestamp} : [${level}] - ${message} \n`;

      let interval = setInterval(() => {
        if (this.isWriting) {
          return;
        }
        this.isWriting = true;
        this.writeLogLine(line);
        clearInterval(interval);
      }, 20);
    });
  }

  protected writeLogLine(line) {
    this.file.writeFile(this.getLogfileDir(), 'consolelog.log', line, {append: true})
      .then(() => {
        this.isWriting = false;
      })
      .catch((e) => {this.localConsole.log('Failed to write logline. Error: ', e); this.isWriting = false; });
  }
}

Brilliant! Just what I need!