price handling fixes affecting orderbuild, pairprice, ordershapes, etc

src/components/chart/ChartOrder.vue

@@ -156,7 +156,7 @@ const maxAmount = computed(()=>{
     return null
   const balance = s.balances[token.a]
   if( !balance )
-    return 0
+    return null
   const divisor = os.amountIsTotal ? 1 : os.tranches
   return balance / 10**token.d / divisor
 })
@@ -165,7 +165,7 @@ const available = computed(()=>{
   return max === null ? '' : `Available: ${maxAmount.value} ${tokenIn.value.s}`
 })
 
-const lastMaxValue = ref(null)
+const lastMaxValue = ref(-1)
 
 function setMax() {
   let amount = maxAmount.value