fix crash with unset arrays in arithmetic constructs ; change to avoid printing foreground job statuses when we don't want to

tests/array.right

@@ -757,6 +757,8 @@ declare -A A=([$'\t']="X" ["*"]="X" [" "]="X" ["@"]="X" )
 declare -A A=(["*"]="X" ["@"]="X" )
 ./array27.sub: line 76: declare: `A[]]=X': not a valid identifier
 declare -A A=(["*"]="X" ["@"]="X" )
+./array27.sub: line 81: y[]: bad array subscript
+./array27.sub: line 81: y[]: bad array subscript
 declare -a bug4=([0]="" [1]="5" [2]="" [3]="1" [4]="")
 declare -a bug=([0]="" [1]="5" [2]="" [3]="1" [4]="")
 declare -a bug2=([0]="")

tests/array27.sub

@@ -76,3 +76,6 @@ for k in ']' '*' '@'; do
    declare "A[$k]=X"
 done
 declare -p A
+
+# empty arrays in arith contexts
+(( y[$none] ))