[Lens] fix passing 0 as static value (#118032)

* [Lens] fix passing 0 as static value

* allow computed static_value to be passed

* Update x-pack/plugins/lens/public/xy_visualization/reference_line_helpers.tsx

Co-authored-by: Marco Liberati <dej611@users.noreply.github.com>

* ci fix

Co-authored-by: Marco Liberati <dej611@users.noreply.github.com>

x-pack/plugins/lens/public/indexpattern_datasource/indexpattern.test.ts

@@ -1696,7 +1696,7 @@ describe('IndexPattern Data Source', () => {
                 isBucketed: false,
                 label: 'Static value: 0',
                 operationType: 'static_value',
-                params: { value: 0 },
+                params: { value: '0' },
                 references: [],
                 scale: 'ratio',
               },

x-pack/plugins/lens/public/indexpattern_datasource/operations/definitions/static_value.test.tsx

@@ -338,6 +338,36 @@ describe('static_value', () => {
       expect(input.prop('value')).toEqual('23');
     });
 
+    it('should allow 0 as initial value', () => {
+      const updateLayerSpy = jest.fn();
+      const zeroLayer = {
+        ...layer,
+        columns: {
+          ...layer.columns,
+          col2: {
+            ...layer.columns.col2,
+            operationType: 'static_value',
+            references: [],
+            params: {
+              value: '0',
+            },
+          },
+        },
+      } as IndexPatternLayer;
+      const instance = shallow(
+        <ParamEditor
+          {...defaultProps}
+          layer={zeroLayer}
+          updateLayer={updateLayerSpy}
+          columnId="col2"
+          currentColumn={zeroLayer.columns.col2 as StaticValueIndexPatternColumn}
+        />
+      );
+
+      const input = instance.find('[data-test-subj="lns-indexPattern-static_value-input"]');
+      expect(input.prop('value')).toEqual('0');
+    });
+
     it('should update state on change', async () => {
       const updateLayerSpy = jest.fn();
       const instance = mount(

x-pack/plugins/lens/public/indexpattern_datasource/operations/definitions/static_value.tsx

@@ -95,7 +95,7 @@ export const staticValueOperation: OperationDefinition<
         arguments: {
           id: [columnId],
           name: [label || defaultLabel],
-          expression: [isValidNumber(params.value) ? params.value! : String(defaultValue)],
+          expression: [String(isValidNumber(params.value) ? params.value! : defaultValue)],
         },
       },
     ];
@@ -118,7 +118,7 @@ export const staticValueOperation: OperationDefinition<
       operationType: 'static_value',
       isBucketed: false,
       scale: 'ratio',
-      params: { ...previousParams, value: previousParams.value ?? String(defaultValue) },
+      params: { ...previousParams, value: String(previousParams.value ?? defaultValue) },
       references: [],
     };
   },

x-pack/plugins/lens/public/xy_visualization/reference_line_helpers.test.ts

@@ -120,6 +120,32 @@ describe('reference_line helpers', () => {
       ).toBe(100);
     });
 
+    it('should return 0 as result of calculation', () => {
+      expect(
+        getStaticValue(
+          [
+            {
+              layerId: 'id-a',
+              seriesType: 'area',
+              layerType: 'data',
+              accessors: ['a'],
+              yConfig: [{ forAccessor: 'a', axisMode: 'right' }],
+            } as XYLayerConfig,
+          ],
+          'yRight',
+          {
+            activeData: getActiveData([
+              {
+                id: 'id-a',
+                rows: [{ a: -30 }, { a: 10 }],
+              },
+            ]),
+          },
+          hasAllNumberHistogram
+        )
+      ).toBe(0);
+    });
+
     it('should work for no yConfig defined and fallback to left axis', () => {
       expect(
         getStaticValue(

x-pack/plugins/lens/public/xy_visualization/reference_line_helpers.tsx

@@ -104,15 +104,14 @@ export function getStaticValue(
   ) {
     return fallbackValue;
   }
-  return (
-    computeStaticValueForGroup(
-      filteredLayers,
-      accessors,
-      activeData,
-      groupId !== 'x', // histogram axis should compute the min based on the current data
-      groupId !== 'x'
-    ) || fallbackValue
+  const computedValue = computeStaticValueForGroup(
+    filteredLayers,
+    accessors,
+    activeData,
+    groupId !== 'x', // histogram axis should compute the min based on the current data
+    groupId !== 'x'
   );
+  return computedValue ?? fallbackValue;
 }
 
 function getAccessorCriteriaForGroup(