Bug: Calculator app crashes or give wrong results on edge-cases

[arduino12]

Describe the bug
The calculator app crashes or give wrong results on edge-cases invalid inputs.

To Reproduce
Here are some invalid inputs that crashes it:
")"
")("
"1+1)"

Here are some invalid inputs that wrongly results in "0":
"("
"/"
"*"
"-"
"+"
"1/0"
"0/0"

Here are some invalid inputs that wrongly results in "1":
")1+1("

Expected behavior
Print an error message or the correct answer.

Details (please complete the following information):

ESP type: ESP32
Device: CYD 2432S028R
Tactility version: 0.5.0
Additional context
Also adding a decimal point button on the way will be nice.

[KenVanHoeylandt]

Thank you for the extensive report! I'll get this fixed.