- string dummy = str->substr (i, j);
- string ligature = robust_scm2string
- (ly_assoc_get (ly_string2scm (dummy),
- replacement_alist, SCM_BOOL_F), "");
- if (ligature != "")
- str->replace (i, j, ligature);
+ if (j > str.size () - i)
+ continue;
+ string dummy = str.substr (i, j);
+ SCM ligature = ly_assoc_get (ly_string2scm (dummy),
+ replacement_alist, SCM_BOOL_F);
+ if (scm_is_true (ligature))
+ str.replace (i, j, robust_scm2string (ligature, ""));