Search highlight (red text marker) extends to entire field when editing searched word

[joshirio]

Steps to reproduce:

1. search for some text (like "ea")
2. edit the word containing the searched text (like "leave" -> "leawe")
3. go to next search result (next toolbar button)
4. now the entire field is marked in red

[joshirio]

Looks like this is a Qt bug because Symphytum is basically using the same code listed as example to highlight searched characters in a QTextEdit https://doc.qt.io/qt-5/richtext-common-tasks.html#finding-text

symphytum/widgets/form_widgets/textformwidget.cpp

Line 118 in 79f1de2

while (!highlightCursor.isNull() && !highlightCursor.atEnd()) {