Prevent crash on splitting the shortest possible measure

Backport of musescore#8894, part 2

Author: Jojo-Schmitz

libmscore/mscore.cpp

@@ -143,6 +143,7 @@ std::vector<MScoreError> MScore::errorList {
       { CANNOT_SPLIT_TUPLET,             "t2", QT_TRANSLATE_NOOP("error", "Cannot split tuplet")                                                   },
       { CANNOT_SPLIT_MEASURE_FIRST_BEAT, "m1", QT_TRANSLATE_NOOP("error", "Cannot split measure here:\n" "First beat of measure")                  },
       { CANNOT_SPLIT_MEASURE_TUPLET,     "m2", QT_TRANSLATE_NOOP("error", "Cannot split measure here:\n" "Cannot split tuplet")                    },
+      { CANNOT_SPLIT_MEASURE_TOO_SHORT,  "m3", QT_TRANSLATE_NOOP("error", "Cannot split measure here:\n" "Measure would be too short")             },
 
       { NO_DEST,                         "p1", QT_TRANSLATE_NOOP("error", "No destination to paste")                                               },
       { DEST_TUPLET,                     "p2", QT_TRANSLATE_NOOP("error", "Cannot paste into tuplet")                                              },

libmscore/mscore.h

@@ -248,6 +248,7 @@ enum MsError {
       CANNOT_SPLIT_TUPLET,
       CANNOT_SPLIT_MEASURE_FIRST_BEAT,
       CANNOT_SPLIT_MEASURE_TUPLET,
+      CANNOT_SPLIT_MEASURE_TOO_SHORT,
       NO_DEST,
       DEST_TUPLET,
       TUPLET_CROSSES_BAR,

libmscore/splitMeasure.cpp

@@ -36,7 +36,6 @@ void Score::cmdSplitMeasure(ChordRest* cr)
 
 //---------------------------------------------------------
 //   splitMeasure
-//    return true on success
 //---------------------------------------------------------
 
 void Score::splitMeasure(Segment* segment)
@@ -111,7 +110,7 @@ void Score::splitMeasure(Segment* segment)
       if (ticks1.denominator() < measure->ticks().denominator()) {
             if (measure->ticks().denominator() % m1->timesig().denominator() == 0) {
                   int mult = measure->ticks().denominator() / ticks1.denominator();
-                  // *= operator audomatically reduces via GCD, so rather do literal multiplication:
+                  // *= operator automatically reduces via GCD, so rather do literal multiplication:
                   ticks1.setDenominator(ticks1.denominator() * mult);
                   ticks1.setNumerator(ticks1.numerator() * mult);
                   }
@@ -123,6 +122,10 @@ void Score::splitMeasure(Segment* segment)
                   ticks2.setNumerator(ticks2.numerator() * mult);
                   }
             }
+      if (ticks1.denominator() > 128 || ticks2.denominator() > 128) {
+            MScore::setError(CANNOT_SPLIT_MEASURE_TOO_SHORT);
+            return;
+            }
       m1->adjustToLen(ticks1, false);
       m2->adjustToLen(ticks2, false);
       range.write(this, m1->tick());