Fix edge case when there is only 1 link

app/pdf-viewer/buffer.py

@@ -547,7 +547,7 @@ class PdfViewerWidget(QWidget):
     def generate_random_key(self, count):
         letters = "ASDFHJKLQWEIOP"
         key_list = []
-        key_len = math.ceil(math.log(count) / math.log(len(letters)))
+        key_len = 1 if count == 1 else math.ceil(math.log(count) / math.log(len(letters)))
         while count > 0:
             key = ''.join(random.choices(letters, k=key_len))
             if key not in key_list:

core/js/get_markers.js

@@ -65,7 +65,7 @@
     function generateKeys(markerContainer) {
         let letters = ['A', 'S', 'D', 'F', 'H', 'J', 'K', 'L', 'Q', 'W', 'E', 'O', 'P', 'N', 'M', 'X', 'C' ];
         let linkNum = markerContainer.children.length;
-        let keyLen = Math.ceil(Math.log(linkNum)/Math.log(letters.length));
+        let keyLen = linkNum == 1 ? 1 : Math.ceil(Math.log(linkNum)/Math.log(letters.length));
         let keys = [];
         while(linkNum > 0) {
             let k = "";