BugFix for app crashing when the ln invoice is blank

app/src/main/java/com/vitorpamplona/amethyst/service/lnurl/LightningAddressResolver.kt

@@ -176,7 +176,7 @@ class LightningAddressResolver() {
                                 null
                             }
 
-                            lnInvoice?.get("pr")?.asText()?.let { pr ->
+                            lnInvoice?.get("pr")?.asText()?.ifBlank { null }?.let { pr ->
                                 // Forces LN Invoice amount to be the requested amount.
                                 val invoiceAmount = LnInvoiceUtil.getAmountInSats(pr)
                                 if (invoiceAmount.multiply(BigDecimal(1000)).toLong() == BigDecimal(milliSats).toLong()) {

app/src/main/java/com/vitorpamplona/amethyst/service/lnurl/LnInvoiceUtil.kt

@@ -103,7 +103,7 @@ object LnInvoiceUtil {
         try {
             decodeUnlimitedLength(invoice) // checksum must match
         } catch (e: AddressFormatException) {
-            throw IllegalArgumentException("Cannot decode invoice", e)
+            throw IllegalArgumentException("Cannot decode invoice: $invoice", e)
         }
 
         val matcher = invoicePattern.matcher(invoice)