old eressea executable has problems with non-existing lua spells.

src/common/kernel/battle.c

@@ -1482,13 +1482,16 @@ do_combatmagic(battle *b, combatmagic_t was)
       const spell * sp = co->sp;
       int level = co->level;
       double power = co->force;
-
+      if (sp->sp_function==NULL) {
+        log_error(("spell '%s' has no function.\n", sp->sname));
+      } else {
         level = ((cspell_f)sp->sp_function)(fig, level, power, sp);
         if (level > 0) {
           pay_spell(fig->unit, sp, level, 1);
         }
       }
     }
+  }
   for (spellrank = 0; spellrank < MAX_SPELLRANK; spellrank++) {
     free_castorders(cll[spellrank]);
   }
@@ -1561,11 +1564,15 @@ do_combatspell(troop at, int row)
     return;
   }
 
+  if (sp->sp_function==NULL) {
+    log_error(("spell '%s' has no function.\n", sp->sname));
+  } else {
     level = ((cspell_f)sp->sp_function)(fi, level, power, sp);
     if (level > 0) {
       pay_spell(mage, sp, level, 1);
       at.fighter->action_counter++;
     }
+  }
 }
 
 
@@ -1584,7 +1591,11 @@ do_extra_spell(troop at, const att *a)
 
   /* nur bei Monstern können mehrere 'Magier' in einer Einheit sein */
   power = sp->level * au->number;
+  if (sp->sp_function==NULL) {
+    log_error(("spell '%s' has no function.\n", sp->sname));
+  } else {
     ((cspell_f)sp->sp_function)(fi, sp->level, power, sp);
+  }
 }
 
 static int

src/common/kernel/magic.c

@@ -202,7 +202,6 @@ static int
 read_mage(attrib * a, FILE * F)
 {
   int i, mtype;
-  boolean update = false;
   sc_mage * mage = (sc_mage*)a->data.v;
   char spname[64];
 
@@ -1355,7 +1354,11 @@ do_fumble(castorder *co)
   case 5:
   case 6:
     /* Spruch gelingt, aber alle Magiepunkte weg */
+    if (sp->sp_function==NULL) {
+      log_error(("spell '%s' has no function.\n", sp->sname));
+    } else {
       ((nspell_f)sp->sp_function)(co);
+    }
     set_spellpoints(u, 0);
     ADDMSG(&u->faction->msgs, msg_message("patzer4", "unit region spell",
       u, r, sp));
@@ -1366,7 +1369,11 @@ do_fumble(castorder *co)
   case 9:
   default:
     /* Spruch gelingt, alle nachfolgenden Sprüche werden 2^4 so teuer */
+    if (sp->sp_function==NULL) {
+      log_error(("spell '%s' has no function.\n", sp->sname));
+    } else {
       ((nspell_f)sp->sp_function)(co);
+    }
     ADDMSG(&u->faction->msgs, msg_message("patzer5", "unit region spell",
       u, r, sp));
     countspells(u, 3);
@@ -2758,7 +2765,12 @@ magic(void)
         /* zuerst bezahlen, dann evt in do_fumble alle Aura verlieren */
         fumbled = true;
       } else if (co->force>0) {
+        if (sp->sp_function==NULL) {
+          log_error(("spell '%s' has no function.\n", sp->sname));
+          co->level = 0;
+        } else {
           co->level = ((nspell_f)sp->sp_function)(co);
+        }
         if (co->level <= 0) {
           /* Kosten nur für real benötige Stufe berechnen */
           continue;

src/eressea/lua/unit.cpp

@@ -197,7 +197,12 @@ unit_castspell(unit& u, const char * name)
       co->par = NULL;
       co->rt = u.region;
       co->sp = sp;
+      if (sp->sp_function==NULL) {
+        log_error(("spell '%s' has no function.\n", sp->sname));
+        co->level = 0;
+      } else {
         sp->sp_function(co);
+      }
       free(co);
     }
     slist=slist->next;