Fix some lint hints from the package very_good_analysis

[dan-blank]

Hi there,

First of, thank you very much for this repository! I am currently building some tracker app for my Android phone and for that I needed to be able to enter data without unlocking my phone. It has been quite some time that I did something with mobile development, so having this project available saved me a ton of work!! :)

I've submitted this PR to fix some linting issues I encountered while setting up the project. I'm planning to fork this as a base for my tracker app. I cleaned them up for my own work, and thought I'd offer the lint fixes back in case you find them useful too.

As for testing, I tested it manually on my pixel phone.

Again, thanks a lot!

[dan-blank]

@devrahul-2508 short update, just in case: I messed up a bit and developed my addition on the master branch, so they showed up in this PR aswell until now. I created a new branch, so now this PR only contains the changes that I want to contribute back initially.

Again, thanks for your great work! :)