Fix checks for non-set date/time values

src/app/HealthCertificateRecovery.qml

@@ -38,7 +38,7 @@ ColumnLayout {
         }
         QQC2.Label {
             text: certificate.dateOfBirth.toLocaleDateString(Qt.locale(), Locale.ShortFormat)
-            visible: certificate.dateOfBirth.getTime() != 0
+            visible: !isNaN(certificate.dateOfBirth.getTime())
             Kirigami.FormData.label: i18n("Date of birth:")
         }
 
@@ -85,7 +85,7 @@ ColumnLayout {
         QQC2.Label {
             text: certificate.certificateExpiryDate.toLocaleString(Qt.locale(), Locale.ShortFormat)
             Kirigami.FormData.label: i18n("Expires:")
-            visible: certificate.certificateExpiryDate.getTime() != 0
+            visible: !isNaN(certificate.certificateExpiryDate.getTime())
         }
         Kirigami.Icon {
             source: {

src/app/HealthCertificateTest.qml

@@ -38,7 +38,7 @@ ColumnLayout {
         }
         QQC2.Label {
             text: certificate.dateOfBirth.toLocaleDateString(Qt.locale(), Locale.ShortFormat)
-            visible: certificate.dateOfBirth.getTime() != 0
+            visible: !isNaN(certificate.dateOfBirth.getTime())
             Kirigami.FormData.label: i18n("Date of birth:")
         }
 
@@ -103,7 +103,7 @@ ColumnLayout {
         QQC2.Label {
             text: certificate.certificateExpiryDate.toLocaleString(Qt.locale(), Locale.ShortFormat)
             Kirigami.FormData.label: i18n("Expires:")
-            visible: certificate.certificateExpiryDate.getTime() != 0
+            visible: !isNaN(certificate.certificateExpiryDate.getTime())
         }
         Kirigami.Icon {
             source: {

src/app/HealthCertificateVaccination.qml

@@ -38,7 +38,7 @@ ColumnLayout {
         }
         QQC2.Label {
             text: certificate.dateOfBirth.toLocaleDateString(Qt.locale(), Locale.ShortFormat)
-            visible: certificate.dateOfBirth.getTime() != 0
+            visible: !isNaN(certificate.dateOfBirth.getTime())
             Kirigami.FormData.label: i18n("Date of birth:")
         }
 
@@ -102,7 +102,7 @@ ColumnLayout {
         QQC2.Label {
             text: certificate.certificateExpiryDate.toLocaleString(Qt.locale(), Locale.ShortFormat)
             Kirigami.FormData.label: i18n("Expires:")
-            visible: certificate.certificateExpiryDate.getTime() != 0
+            visible: !isNaN(certificate.certificateExpiryDate.getTime())
         }
         Kirigami.Icon {
             source: {